EARLY MAN AND HOMININ PALEONTOLOGY
Olduvai Gorge Paleontology or palaeontology is the scientific study of life that existed prior to or during the Holocene period (roughly 11,700 years ago). It includes the search for, study and analysis of fossils. A paleontologist is a paleontology scientist. Hominin paleontologists study hominins, which first appeared roughly four million years ago.
Hominins are defined as creatures that stand upright and walk and run primarily on two legs, while apes are creatures that hunch over and, although capable of walking on two legs, prefer to use their arms when moving on the ground. Before the mid 2000s, scientists often referred to hominins as hominids. Hominids are all modern and extinct great apes: gorillas, chimps, orangutans and humans, and their immediate ancestors. Not gibbons. Hominins are any species of early human that is more closely related to humans than chimpanzees, including modern humans themselves.
Many important discoveries and insights into our human ancestors are taking place in the field of genetics and ground zero for this activity is the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany. Elizabeth Kolbert wrote in The New Yorker: “The Max Planck Institute... is a large, mostly glass building shaped a bit like a banana. The institute sits at the southern edge of the city, in a neighborhood that still very much bears the stamp of its East German past. If you walk down the street in one direction, you come to a block of Soviet-style apartment buildings; in the other, to a huge hall with a golden steeple, which used to be known as the Soviet Pavilion. (The pavilion is now empty.) In the lobby of the institute there’s a cafeteria and an exhibit on great apes. A TV in the cafeteria plays a live feed of the orangutans at the Leipzig Zoo.” [Source: Elizabeth Kolbert, The New Yorker, August 15, 2011]
Scientists have found fossils of 5,000 individual hominins as far back as 4.4 million years, perhaps 7 million years. Famous discoveries include Java Man, Peking Man, the Taung Child, Lucy and the first Neanderthals (See Java Man, Peking Man, Taung Child and Neanderthals. Pitsdown Man is a famous fraud.
Websites and Resources on Hominins and Human Origins: Smithsonian Human Origins Program humanorigins.si.edu ; Institute of Human Origins iho.asu.edu ; Becoming Human University of Arizona site becominghuman.org ; Talk Origins Index talkorigins.org/origins ; Last updated 2006. Hall of Human Origins American Museum of Natural History amnh.org/exhibitions ; Wikipedia article on Human Evolution Wikipedia ; Human Evolution Images evolution-textbook.org; Hominin Species talkorigins.org ; Paleoanthropology Links talkorigins.org ; Britannica Human Evolution britannica.com ; Human Evolution handprint.com ; National Geographic Map of Human Migrations genographic.nationalgeographic.com ; Humin Origins Washington State University wsu.edu/gened/learn-modules ; University of California Museum of Anthropology ucmp.berkeley.edu; BBC The evolution of man" bbc.co.uk/sn/prehistoric_life; "Bones, Stones and Genes: The Origin of Modern Humans" (Video lecture series). Howard Hughes Medical Institute.; Human Evolution Timeline ArchaeologyInfo.com ; Walking with Cavemen (BBC) bbc.co.uk/sn/prehistoric_life ; PBS Evolution: Humans pbs.org/wgbh/evolution/humans; PBS: Human Evolution Library www.pbs.org/wgbh/evolution/library; Human Evolution: you try it, from PBS pbs.org/wgbh/aso/tryit/evolution; John Hawks' Anthropology Weblog johnhawks.net/ ; New Scientist: Human Evolution newscientist.com/article-topic/human-evolution; Fossil Sites and Organizations: The Paleoanthropology Society paleoanthro.org; Institute of Human Origins (Don Johanson's organization) iho.asu.edu/; The Leakey Foundation leakeyfoundation.org; The Stone Age Institute stoneageinstitute.org; The Bradshaw Foundation bradshawfoundation.com ; Turkana Basin Institute turkanabasin.org; Koobi Fora Research Project kfrp.com; Maropeng Cradle of Humankind, South Africa maropeng.co.za ; Blombus Cave Project web.archive.org/web; Journals: Journal of Human Evolution journals.elsevier.com/; American Journal of Physical Anthropology onlinelibrary.wiley.com; Evolutionary Anthropology onlinelibrary.wiley.com; Comptes Rendus Palevol journals.elsevier.com/ ; PaleoAnthropology paleoanthro.org.
Scientists that study hominins are known for the ferocious critiques that they hurl at their colleagues. The field is highly competitive and careers can be made with a single discovery. Jon Mooallemjan wrote in the New York Times magazine: “The study of human origins, I found, is riddled with vehement disagreements and scientists who readily dismantle the premises of even the most straightforward-seeming questions. [Source: Jon Mooallemjan, New York Times magazine, January 11, 2017 ||*||]
Jennifer Raff wrote in The Guardian: “Keeping pace with new developments in the field of human evolution these days is a daunting prospect. It seems as though every few weeks there’s an announcement of exciting new findings from hominin fossils, or the recovery of an ancient genome that significantly impacts our understanding of our species’ history. [Source: Jennifer Raff, The Guardian, July 18, 2017. Raff is a geneticist who specialises in the study of human variation among contemporary and ancient populations |=|]
“The best way to keep up is by regularly revisiting and reassessing a few core questions. When and where did our species first appear? How and where did we migrate? What was our relationship to our (now-extinct) hominin relatives? What evolutionary and cultural factors influenced our histories? How do new findings change the answers to these questions? Are they generally accepted by the relevant community of experts, or are they provisional or controversial?” |=|]
Describing a symposium on early hominins at the Turkana Basin Institute in Kenya in August 2014, Jamie Shreeve wrote in National Geographic: “For four days the scientists huddled together in a spacious lab room, its casement windows open to the breezes, casts of all the important evidence for early Homo spread out on tables. One morning Meave Leakey (who’s also a National Geographic explorer-in-residence) opened a vault to reveal brand-new specimens found on the east side of the lake, including a nearly complete foot. When it was his turn to speak, Bill Kimbel of the Institute of Human Origins described a new Homo jaw from Ethiopia dated to 2.8 million years ago—the oldest member of our genus yet. Archaeologist Sonia Harmand of Stony Brook University dropped an even bigger bombshell—the discovery of dozens of crude stone tools near Lake Turkana dating to 3.3 million years ago. If stone tools originated half a million years before the first appearance of our genus, it would be hard to argue anymore that the defining characteristic of Homo was its technological ingenuity.” [Source: Jamie Shreeve, National Geographic, September 2015 /+]
Stone Age Periods
1835 winged hominin hoax Pleistocene 1,000,000 (or 500,000) to 10,000 years ago, period of ice ages.
Paleolithic, 500,000-10,000 B.C., refers to cultures of the Pleistocene period
Lower Paleolithic, 500,000-250,000 B.C..
Middle Paleolithic, 250,000-60,000 B.C..
Upper Paleolithic, 60,000-10,000 B.C..
Mesolithic is sometimes used to describe a period between the Paleolithic and Neolithic periods.
Neolithic (from about 9500 to 6000 B.C.), last stage of stone age, the use of polished stone tools and the beginning of agriculture
History of Paleontology
One of the earliest published reports on prehistoric man was made in 1800 by English antiquarian John Frere. In his “Account of Flint Weapons Discovered at Hoxne in Suffolk” he described flint hand axes found below a layer of mammoth bones by workmen digging up clay for bricks and concluded the tools were “fabricated and used by a people who had not the use of metals” and lived in “a very remote period indeed, even beyond that of the present world.” The report was largely ignored. In the 1840s, French prehistorian Jacques Boucher de Perthese trained workmen to search for stone axes.
The science of paleontology owes it origin to Charles Darwin’s book "On the Origin of Species”, which was published in 1859 and shook conventional thinking with the theories of evolution and natural selection. Studies of geology had already opened mind to enormity of time and raised questions about the Biblical time line. The first remains ever found of a prehistoric human ancestor were found in 1856 in the Neander Valley in Germany. Darwin provided a theory and framework to attach these discoveries and others that followed.
The words Paleolithic and Neolithic, meaning “Old Stone Age” and “New Stone Ages,” and the word “cave-man” were coined by John Lubbock, Darwin’s only student. Many of the those who study early man and hominin today are called paleoanthropologists.
Andre Lero-Gourhan revolutionized the practice of excavations by recognizing that vertical digs destroy the context of a site. Over 20 years (1964-1984) he and his students painstakingly excavated “scraping away the soil in small horizontal squares and making notes of where everything was located, in the 12,000-year-old site of Pincevent, offering of the most detailed picture up to that point of life in the Paleolithic period.
Hominins, the Missing Link and the Evolution of Man
Hominins are defined as creatures that stand upright and walk and run primarily on two legs, while apes are creatures that hunch over and, although capable of walking on two legs, prefer to use their arms when moving on the ground. The earliest hominins, the genus Australopethecus, possesses long arms, short legs, a large small brain and a large face. These creatures would appear to us today as more ape-like than human-like. So far these species have been discovered only in eastern, northern and south Africa.
There are two major groups, or genera of hominins: “Australopithecus” , which lived between 4 million and 1 million years ago and includes a number of species; and “Homo” , which appeared around 2.5 million years ago and includes, “Homo habilis” , “Homo erectus “ and “Homo sapiens” (modern man).
Scientists describe Africa is the "cradle of mankind" because all of the oldest hominin remains have been found there. In the mid 2000s, scientists began calling homonids “homonins.”
Modern man (us) appeared at least 100,000 years ago, maybe 200,000 years ago, and are believed to have evolved from: 1) Australopithecus aferenis (3.8 to 3 million-years-ago); 2) Australopithecus africanus (3 to 2 million-years-ago); 3) Homo habilis (2 to 1.5 million-years-ago), and 4) Homo erectus (1.8 to .5 million-years-ago). Most Scientists believe that the other ancient man species led to dead ends. There is a lot of controversy and debate in this field. The study of early man has often been posed as a quest for “the missing link.” Most scientists bristle at the term. Tim White, a paleoanthropologist at the University of California, Berkeley, told National Geographic, “The term is wrong in so many ways, it’s hard to know where to begin. Worst all is the implication that at some point there existed something halfway between chimp and human. That’s a popular misconception that has plagued evolutionary science from the beginning.”
Messy Models of the Evolution of Man
Early attempts to plot the course of human evolution tried to present nice neat linear models with one species leading directly to another. The more discoveries that were made the less the neat models became.
Modern models of human evolution look like groups of trees with lots of entangled branches — some that lead to dead ends and others that continue on and interconnect to other branches. In the old days many thought who studied early man were regarded as “lumpers” because they tended to lump discoveries into group. In recent years they have taken a backseat too “splitters,” who shy away from grouping new discoveries and instead often define them as new, separate species.
New discoveries have also debunked theories that human evolution was marked by a series of nice, neat progressions and advancements. Sometimes new discoveries dated to a certain period seem more primitive than older finds.
Some features in one species appear and then disappear and then re-emerged in later species, making the features insignificant as some sort of milestone. Bernard Wood of George Washington University told Newsweek, “Similar traits evolved more than once, which means you can’t use them as gold-plated evidence that one fossil is descended from another or that having an advanced trait means a fossil was a direct ancestor of modern humans.”
Lee Berger, a paleoanthropologist at the University of the Witwatersrand, says that rather than a tree branching from a single root, the best metaphor for human evolution is a braided stream: a river that divides into channels, only to merge again downstream. Jamie Shreeve wrote in National Geographic: “Similarly, the various hominin types that inhabited the landscapes of Africa must at some point have diverged from a common ancestor. But then farther down the river of time they may have coalesced again, so that we, at the river’s mouth, carry in us today a bit of East Africa, a bit of South Africa, and a whole lot of history we have no notion of whatsoever. Because one thing is for sure: If we learned about a completely new form of hominin only because a couple of cavers were skinny enough to fit through a crack in a well-explored South African cave, we really don’t have a clue what else might be out there.” [Source: Jamie Shreeve, National Geographic, September 2015 /+]
Fossilized Bones and Hominins
early theory of evolution Very few living organisms leave behind fossil traces. The bones and remains of most ancient creatures decay or wither away to dust. A particular set of circumstances has to unfold for bones to be preserved after a creature dies.
Since the number of homonids is very small when compared to the total number of animals that have existed in the history of the world their bones are particularly hard to find. Teeth enamel is the hardest substance in the human body and thus hominin teeth are most common hominin fossils.
For the bones to be persevered ideally they have to be picked clean (by scavengers like hyenas) of material which might cause the bone to rot, and then be covered quickly by sediment (by material carried in a flash flood, for example) before they decay in the sun. In many cases, after thousands of years the water-soluble materials in the bones are leeched away, leaving behind fossils. By this time additional layers of sediment have covered the bones. For the fossils to be found they need to be exposed in a place where a scientist or fossil hunter can find them. Geological processes such as uplift and erosion have to occur to bring the fossils to the surface. [Source: Kenneth Weaver, National Geographic, November 1985 [┹]
Discovering Early Hominin Bones
Important discoveries are very rare events. Even in the richest sites, hominin fossil generally make up less than 0.1 percent of all fossils found. Some scientists spend their whole life searching without finding anything.
Few discoveries have been made areas with dense vegetation. Find are usually made in arid, sparsely vegetated areas where seasonal rains erode the landscape, exposing fossil bones. Many discoveries have been on the surface of the earth by sharp-eyed fossil hunters — many of them people hired by scientists not the scientists themselves — who cover large areas on foot. Only highly promising areas are excavated.
Paleoanthropologists, paleontologists, archaeologists and their helpers search for bone fragments exposed by erosions. Once a bone has been found or a promising site has been selected, paleontologists mark discoveries with flags, so their context can be recorded and the location can be meticulously examined. Obvious fossils such as teeth are picked up by hand. Fossils encased in rock are removed dental picks and porcupine quills. Soil is sieved for small pieces teeth and bone. It is very slow work. When prehistoric bones are found they are immediately covered in plaster for their protection.
Hominin fossils tend to be very delicate. Many bones are found crushed. Some turn to powder when they are extracted. When bones are found scientists and fossil hunters often repeatedly douse them with hardeners, clear away the soil or cut away the rock around them, and immediately seal the bones or wrap them in plaster. Many hominin fossils found in east Africa show evidence of being ravaged by hyenas after death.
Assembling and Working with Hominin Bones
bones in stone Assembling hominin bone fragments and making sense of what is found after bones are found is a difficult, time consuming process. In most cases the process involves shifting through large amounts of dirt, sand and rocks near a site where an initial discovery is made to find bones and bone fragments that belong to the same specimen and other member of its species. After that scientists work out where layers containing similar fossils might have eroded to and then sifting through the dirt, sand and rocks in these places to look for more bones and fragments. After that stage is completed — a process that can take months — the pieces are taken to a lab and fitted together, a process that can take years.
In some rare situations bones are found fossilized in rocks like those of dinosaurs bones. This doesn’t happen as often with hominins because the sediments they are found in are not that old and generally have not had enough time to form into rock. When such a hominin fossil is found it is considered a great discovery because the bones are found together in one place and looking high and low for the pieces is not necessary. On the down side though it can be painstaking work — done largely with dental tools — to remove the bones from the rock without damaging the bones. Again this process takes years and often require even more time to place fragments together and work out where the bones go in relation to the others.
In the lab the fossil fragments are sorted on a tray and the material the fragments are located in is moistened with acetone which makes it easy to distinguish fossil from rock. Under a microscope rock is removed from rock-encased fossils grain by grain using engraving tools. Sometimes CT scans and 3-D reconstruction software are used to figure out how bones and bone fragments — too delicate to handle — fit together.
Recently scientists have started using huge, expensive synchotors, normally used in nuclear particle physics, to zap hominin bones and teeth with radiation and see what turns up. The technique is especially useful in analyzing teeth to see what is revealed in each layer of enamel that were applied in various stages of a subject’s life. Using this method scientists have gained insight into what subjects ate, their health and other information at different times in their life sort of like the way tree rings can supply information about fires and droughts as well as age.
Scientists often can determine how old a fossilized hominin was when it died by noting how worn the teeth are. Pitted tooth enamel is an indicator or starvation and malnutrition. The easiest way to determine the sex is by examining the pelvic bones. Females have large round openings, large enough to accommodate the head of a baby. Males have a heart-shaped opening.
Lucy bones Archaeologists crawl, kneel and laboriously brush away dirt with a brush from objects they unearth. Soil, sand and excavated material are sifted through screen to retrieve small artifacts.
Archaeologists often dig a series of trial trenches to figure out the best places to excavate. Photographs are taken of each phase of the work for future reference. Soil is sifted so that small objects are not overlooked. When something is found it is often swept with a brush and removed with a trowel so it doesn’t break.
Artifacts are brought into workshops are catalogued. Delicate objects are restored in situ. Other objects are restored in the work room or laboratory.
It is very important to record the position of all the objects that are found. The vertical position of an object, as defined by the layer in the earth, or strata, where it is found reveals its date or at least it relations to what came before and after it. Archaeologists carefully remove earth layer by layer when they are excavating so they can determine the date or period of objects and not mix them up with objects from other periods.
The strata are often look like the layers of a layer cake, with the oldest layers being the ones that are the deepest in the earth. Each layer and the locations of artifacts are carefully measured, often with surveying equipment. The layers can be dated by using the dating methods listed below.
The horizontal position of an object and it locations in relation to other objects often give clues to what the object is used for. The locations of each significant object found are recorded using a grid system that usually can be overlaid on the excavation site. These days measurements can be done with lasers and excavation records and survey data can quickly be transferred to computer to create a three-dimensional model of excavated objects and their positions.
Modern Archaeology Techniques
Sites are located with ariel surveys and satellite imagery. Satellite images sometimes reveals the outlines of promising sites and trade routes obscured by sands or vegetation cover or sites that are otherwise missed on the ground. Seismological devices used by geologists are widely employed by archeologists.
Foods and drinks from ancient times can be determined by analyzing samples in a spectrometer and looking for organic compounds, especially long-chain lipids, triglycerides and fatty acids that characterize many foods. The presence of beer can be determined by the presence of calcium oxalate (“beerstone”). Wine can be determined by tartaric acid and its salts. Samples can be extracted from pottery and jars with solvents. Specific fatty acids can be markers for meat such goat, mutton and pork. Anisic acid is an indicator of anise, or fennel.
Brains, Faces and Mikhail M. Gerasimov
Paleoneurology is the study of the brains of ancient hominins. This is primarily done by analyzing the structure of the brain by examining the insides hominin skulls and through DNA research of genes linked with brain activity found in both humans and apes.
These days is becoming common to reconstruct faces of ancient hominins using methods pioneered by Mikhail M. Gerasimov (1907- 1970), a Russian archaeologist, paleontologist and sculptor who developed a theory for approximating the faces of Ice Age hunters and famous people like Ivan the Terrible and Tamerlane by analyzing their skull features. His techniques have been adopted by forensics experts around the world to identify victims of murder, war crimes and other atrocities whose bones were found but not identified. Scientists using his techniques have re-created the faces of King Tut, the 9,200-year-old Kennewick Man found in the northwest United States, and all the great czars.
Gerasimov was the not the first to re-create faces based on skulls but was the first to use scientific methods to do Tapping into his vast reservoir of knowledge of facial and skull features based on years of working in forensic science, archaeology and anthropology, he applied strips of clay to a cast of skull to create likeness of skull’s owner. Gerasimov was the inspiration for the brilliant scientist, who helps solve the murder of thee victims who had their faces peeled away in the novel “ Gorky Park” by Martin Cruz Smith and a film based on the novel with William Hurt.
Gerasimov was born in St. Petersburg and grew up in the Siberian city of Irkutsk, As a boy he liked to collect mammoth bones and mix the bones of animals, say, putting a cats skull on the skeleton of a duck. He studied archaeology at Irkutsk University and Leningrad and helped establish the Laboratory for Plastic Reconstruction (now the Institute of Ethnology) in Leningrad. In the early 1940s Gerasimov was sent to Uzbekistan to open the tomb of Tamerlane, an act which is said to have unleashed a curse that unleashed World War II on the Soviet Union.
Techniques Used in Reconstructing Hominin Faces
Scientists using Gerasimov’s techniques begin by making a mold and copy of the skull and inserting pegs cut to average tissue thickness based on sex, race and size of the individual. Glass eyes were added, and clay strips of proper thickness are laid across the skull mold. Features are then added based on information gleaned from facial bones.
With hominin skulls which are mostly collections of fragment glued together, missing sections are reconstructed out of epoxy compounds, and distortions are corrected often by comparing the right and left side. Large missing spots are sculpted in clay based on modern primate anatomy. The glass eyes are inserted early and surrounded by musculature. The shape and size of the nose are calculated from surrounding none attachments. Superficial representations of facial muscles, fats and other tissues are added. The tissue is then covered with a clay skin. Using mold, features are impressed into the surface.
A silicon rubber mold is then made of the entre reconstruction and a new cast is created in urethane rubber. Skin tones are painted onto the finished cast. Hairs are individually punched into the skin and finishing touches are added. After the reconstruction is photographed, the image can be digitally enhanced.
Many scientists who use Gerasimov’s techniques have extensive training an anatomy, osteology and craniology. The key to get a face right is often in the details . Permanent ridges left by face muscles, for example, may provide clues to kind of expression worn on the face most of the time. The nose is often created based on a mirror image of the skeletal structure around the nostrils
Studying Ancient Diets
Ann Gibbons wrote in National Geographic: “Until agriculture was developed around 10,000 years ago, all humans got their food by hunting, gathering, and fishing. As farming emerged, nomadic hunter-gatherers gradually were pushed off prime farmland, and eventually they became limited to the forests of the Amazon, the arid grasslands of Africa, the remote islands of Southeast Asia, and the tundra of the Arctic. Today only a few scattered tribes of hunter-gatherers remain on the planet. [Source: Ann Gibbons, National Geographic, September 2014 /*/]
“That’s why scientists are intensifying efforts to learn what they can about an ancient diet and way of life before they disappear. “Hunter-gatherers are not living fossils,” says Alyssa Crittenden, a nutritional anthropologist at the University of Nevada, Las Vegas, who studies the diet of Tanzania’s Hadza people, some of the last true hunter-gatherers. “That being said, we have a small handful of foraging populations that remain on the planet. We are running out of time. If we want to glean any information on what a nomadic, foraging lifestyle looks like, we need to capture their diet now.” /*/
“So far studies of foragers like the Tsimane, Arctic Inuit, and Hadza have found that these peoples traditionally didn’t develop high blood pressure, atherosclerosis, or cardiovascular disease. “A lot of people believe there is a discordance between what we eat today and what our ancestors evolved to eat,” says paleoanthropologist Peter Ungar of the University of Arkansas. The notion that we’re trapped in Stone Age bodies in a fast-food world is driving the current craze for Paleolithic diets. The popularity of these so-called caveman or Stone Age diets is based on the idea that modern humans evolved to eat the way hunter-gatherers did during the Paleolithic—the period from about 2.6 million years ago to the start of the agricultural revolution—and that our genes haven’t had enough time to adapt to farmed foods.” /*/
Studying Teeth to Gain Information About Diet
Studying teeth — which fortunately are among the more common hominin fossils — offers a lot information about diet and the foods hominin ate especially with the technology and science available today. "The moment we get our adult teeth, they start to wear down. And the rate at which they wear down is very much related to what you eat — especially if you look at the molars," Sireen El Zaatari, a paleoanthropologist at the University of Tübingen in Germany, told NPR. "This food that you're chewing is leaving tiny, tiny marks on your teeth." [Source: Maanvi Singh, NPR, April 29, 2016 \~/]
“Meat — especially cooked meat — is relatively gentle on the chompers, whereas seeds and nuts leave a mark, she says. El Zaatari and her colleagues looked at the teeth of Neanderthals and humans living mainly in Europe throughout the Upper Paleolithic period. "A better way to look at diet is to look at the chemistry of [tooth] enamel," Cachel says. \~/
“Different plants absorb different amounts of carbon isotopes. Scientists can analyze the ratios of various isotopes on ancient enamel to figure out what sorts of fruits, nuts and vegetation our ancient predecessors ate. So the isotopes in tooth enamel can paint a broad picture of what someone ate throughout their life. On the other hand, "the advantage of looking at [dental wear] is that you get a fuller picture of what all they were eating right up to the time when they died," says Shara Bailey, an anthropologist at New York University.” \~/
On a study involving the teeth of several Australopithecus species, Melissa Hogenboom of the BBC wrote: “Their diet was analysed from the chemical make up of their teeth, identifying the carbon isotopes within them. The ratios of different types of carbon atoms, or isotopes, in fossils can give clues to what a fossil creature ate because different foods have different carbon isotope signatures. “What we have is chemical information on what our ancestors ate, which in simpler terms is like a piece of food item stuck between their teeth and preserved for millions of years,” said Dr Zeresenay Alemseged, from the California Academy of Sciences, co-author on two of the papers. “Because feeding is the most important factor determining an organism’s physiology, behaviour and its interaction with the environment, these finds will give us new insight into the evolutionary mechanisms that shaped our evolution.” [Source: Melissa Hogenboom, BBC News, June 4, 2013]
Studies of Chemical Isotopes in Tooth Enamel
Zach Zorich wrote in Archaeology magazine: “Direct evidence that reveals the behavior of the human race's earliest ancestors has been all but impossible for paleoanthropologists to find. Now, however,studies of chemical isotopes in tooth enamel are providing new lines of evidence concerning the lives of early hominins. As tooth enamel forms during the first eight years of life, it absorbs chemicals from the food and water that people consume and, indirectly, from the bedrock in the area where they reside. That chemical signature provides an important record of an individual's life, which scholars are now learning to read. Two recent isotope studies are changing paleoanthropologists' understanding of hominins who lived roughly 2.2 to 1.4 million years ago. [Source: Zach Zorich, Archaeology, Volume 64 Number 5, September/October 2011 ***]
“A study published in Proceedings of the National Academy of Sciences examined the amounts of carbon isotopes in two Paranthropus boisei teeth from eastern Africa. Carbon isotopes reveal details about diet, and the research showed that these individuals dined on grasses and sedges. Previously, P. boisei had been nicknamed Nutcracker Man because paleoanthropologists believed the species' large teeth and powerful jaws were an evolutionary adaptation to eating hard foods. *** “A second study, published in the journal Nature, measured strontium isotopes in the teeth of Australopithecus africanus and Paranthropus robustus from southern Africa. Strontium isotopes offer evidence of the bedrock in an individual's early home area because plants and water absorb strontium from the bedrock, which is then absorbed by tooth enamel. This study showed that females of both species tended to grow up in areas with a different type of bedrock than the places where their teeth were ultimately found. The finding could indicate that females left the social groups they were born into and moved away to live with their mates. ***
“The major impact of this research has less to do with the results of the two studies and more to do with providing paleoanthropologists with a new research tool, according to the University of Colorado's Matthew Sponheimer, who took part in both projects. "If we can be clever enough, we might be able to design ways to get at interesting behaviors that had seemed forever lost," he says.” ***
Studying Teeth Tartar — Dental ‘Calculus’ — of Hominins
Chris Gorski wrote in Inside Science: “Many ancient human teeth, including specimens tens of thousands of years old, still hold onto tiny pieces of food — and even bacteria. Anthropologists are studying the tartar attached to ancient human teeth to learn more about the plants people ate and the pathogens they carried long ago. Tartar, also known as dental calculus, is a hard substance that toothpaste ads promise to obliterate and dentists scrape away. It builds up on human teeth after dental plaque solidifies. A dentist might scrape away 30 milligrams of a patient’s calculus each visit. Sets of teeth from hundreds or thousands of years ago might have up to 20 times that much, a mass roughly equal to a small paperclip. [Source: Chris Gorski, Inside Science, May 30, 2012 /]
“Scientists are only beginning to explore the variety of materials caught in calculus, which preserves organic materials that are often fleetingly preserved in other settings. This allows scientists to address questions that are very difficult to answer using established archaeological methods. “There are so many time periods in human history where we have theories about what they ate but we really have no idea,” said Amanda Henry, a physical anthropologist at the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany. /
“Seeds and grains often degrade slowly and animal bones typically last even longer. But finding direct evidence of vegetable consumption is more difficult. Vegetables such as cabbage and carrots were important foods in medieval Europe, but evidence to confirm their consumption is hard to come by. Reconstructing the full diet for people living in earlier periods is even more difficult. “We know very little about the vegetable and salad portion of the diet,” said Christina Warinner, an archaeological geneticist at University of Zurich’s Centre for Evolutionary Medicine, in Switzerland. “[Studying calculus] could potentially be an entirely new way of approaching that.”“ /
Methodology of Studying Hominin Tooth Tartar
Chris Gorski wrote in Inside Science: “Calculus contains pollen grains and microscopic fossilized plant pieces called phytoliths, in addition to starch grains and even bacteria. Fragments of bacterial DNA found in calculus can help identify specific pathogens that were once present in the mouths of ancient people. The plant evidence can be definitive enough to suggest the species that was consumed, or it may suggest what part of a plant was eaten, such as a fruit or leaf. This can help track the use, spread and evolution of food plants, including agricultural varieties, through time and space. Researchers can examine the calculus directly on the tooth with a microscope. But for further analysis, they carefully scrape the material off ancient teeth with common dental tools to avoid contaminating the samples with modern material. From that scraped-off tartar, they then carefully remove non-organic material to concentrate the food remnants. [Source: Chris Gorski, Inside Science, May 30, 2012 /]
“Scientists use microscopes and molecular methods to examine the samples....Techniques to deduce ancient diets and disease from dental calculus are still being established and verified. Molecules of DNA in dental calculus are often degraded, and the more time has passed, the lower the chance that the sample is pristine, which makes interpretation more complicated. Scientists are also uncertain as to how comprehensively calculus can portray diet. Not all foods that are consumed will be found in calculus. Although finding evidence that a food was in a person’s mouth is significant, it doesn’t necessarily explain how often the food was eaten, or what proportion of the overall diet it represented. “We must be conscious that ancient people did not only eat starchy seeds or tubers; they also ate leaves, flowers, and so on,” said Pagan-Jimenez. What percentage of a person’s diet is represented in that record? We don’t know,” said Henry. “Any technique, you need to work out all the bugs before all academics buy it. /
“Scientists are still forming a full picture of all the components found inside ancient dental calculus, said Warinner. Henry said she planned to examine calculus “for other kinds of plant residues or even animal food residues.” She said that the technique may help solve an important mystery: when humans began cooking their food — answers currently range from a few hundred thousand to more than 1.5 million years ago. /
Kinds of Information Found in Tooth Tartar
Chris Gorski wrote in Inside Science: “Examining the small bits of food they find is challenging some long-held beliefs about ancient peoples and helping to answer significant questions. Henry has been studying Neanderthal diet and working to confirm her initial results that they ate plants regularly. Some researchers have long argued that Neanderthals were primarily carnivores who depended on meat and fat. “We were able to show that [Neanderthals] did eat plant foods and they processed these foods,” said Henry. “It’s the first time we have evidence of what those plant foods are.” “Henry and her collaborators identified grass seeds, tubers that may have been related to water lilies, and at least in a location in present-day Iraq, the foods had been cooked. [Source: Chris Gorski, Inside Science, May 30, 2012 /]
“Jaime Pagan-Jimenez, a Puerto Rico-based anthropologist working at Leiden University in the Netherlands, recently began analyzing calculus to obtain more evidence in his study of diets throughout the Caribbean islands. Pagan-Jimenez had already studied starch grains found in artifacts used to process and cook foods, concluding that the people who first lived on the Caribbean islands were, in at least many cases, cultivating a variety of food plants, such as corn, sweet potato, beans, and more. His findings also challenged the idea that the area’s main food crop was manioc, a root also known as cassava or yucca. The new technique allows him to confirm what foods actually reached the mouth. “We had the chance of seeing directly in the human tooth what plants they were eating at different time periods and sub-regions in the Caribbean islands,” Pagan-Jimenez wrote to Inside Science in an email. That evidence changes the interpretation of other archaeological findings. “It turns out that these tools that we’ve called manioc scrapers were not at all used for processing manioc,” said Henry. /
“Starch grains, such as those found in cooking pots, are well-established evidence of food processing and consumption. Scientists also look for clues about food consumption in the atomic makeup of bones and tooth enamel. However, calculus allows researchers to attain a greater level of detail. “For starch grains studies in archeology, human dental calculus is the last piece of the ‘broad picture’ for acquiring direct information on the whole process of plant preparation and consumption as food,” said Pagan-Jimenez.
Health Information Gleaned from Dental ‘Calculus’
Chris Gorski wrote in Inside Science: “Dental plaque contains all manner of information about an individual’s health. It can contain clues about tuberculosis, stomach ulcers and more. Since calculus is formed from plaque, it seemed natural to Warinner to investigate the preservation of health information. “It seems like a great way to actually access so much health information about ancient peoples that otherwise has been really, really hard to do,” said Warinner. /
“One significant modern change is a highly processed diet, which is often accompanied by fluoridated water. How does the state of modern people’s mouths differ from that of their ancestors? Because calculus can preserve oral bacteria, it opens new doors to scientists. “One of the things we don’t know very well is what actually is our natural or ancestral state of health in our mouth,” said Warinner. “We can look at specific dental diseases and try to understand how they have changed over time.” [Source: Chris Gorski, Inside Science, May 30, 2012 /]
Warinner said that in addition to bacteria from the mouth, calculus also contains bacteria that originated in other areas of the body. These bacteria can provide more information on the array of tiny organisms that inhabit the human body, called the microbiome. Doctors are becoming increasingly aware of the relationship between this collection of flora and human health. Data gathered from genetic material found in samples such as calculus is termed metagenomic, and can greatly enhance scientists’ ability to research the historical microbiome. “[Calculus] allows us unparalleled access to these more distant organ systems that we’ve almost never had access to in the archaeological record except in some exceptional circumstances,” said Warinner. /
““The idea that metagenomic data from archaeological dental calculus can provide a glimpse of ancient human diet and health is very clever, and if validated, it will be a very exciting discovery!” wrote Cecil Lewis, a molecular anthropologist at the University of Oklahoma, in an email. /
Image Sources: Wikimedia Commons
Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Natural History magazine, Archaeology magazine, The New Yorker, Time, BBC, The Guardian, Reuters, AP, AFP and various books and other publications.
Last updated September 2018